Polydopamine Nanoparticles Prepared Using Redox-Active Transition Metals.

Autoxidation of dopamine to polydopamine by dissolved oxygen is a slow process that requires highly alkaline conditions. Polydopamine can be formed rapidly also in mildly acidic and neutral solutions by using redox-active transition-metal ions. We present a comparative study of polydopamine nanoparticles formed by autoxidation and aerobic or anaerobic oxidation in the presence of Ce(IV), Fe(III), Cu(II), and Mn(VII).

Effects of pH and Oxidants on the First Steps of Polydopamine Formation: A Thermodynamic Approach.

We present a general thermodynamic top-down analysis of the effects of oxidants and pH on dopamine oxidation and cyclization, supplemented with UV-vis and electrochemical studies. The model is applicable to other catecholamines and various experimental conditions. The results show that the decisive physicochemical parameters in autoxidation are the p K values of the semiquinone and the amino group in the oxidized quinone.